The continuing expansion of the communications industry, particularly the rapidly increasing use of telephone networks by non industrial and non commercial enterprises, has brought about requirements for standardizing and simplifying user access to an ever increasing variety of equipment and services. Considering the many different types of devices currently available and the desirability that users be able to install and maintain their own equipment, one of these requirements is that there be a uniform scheme through which all users, including subscribers and craftspersons, are able to test a telephone line by means of a noncomplicated ringback procedure. While the more recently developed systems provide a high degree of flexibility and functionality, older central office equipment is performance limited, so that only service personnel may be permitted access to the ringback function. Moreover, for each respective code (usually the first three digits of a seven digit number) associated with different dedicated equipment through which the user accesses the ringback function, the telephone company loses the capability to provide service to approximately ten thousand subscriber lines, thereby accelerating the need to subdivide area code regions.